CN108047340A - A kind of method of modifying for improving the slowly digestible energy of starch - Google Patents

Abstract

The invention discloses a modification method for improving slow digestibility of starch, which belongs to the field of bio-modified starch. The present invention utilizes starch branching enzyme to transform the elongated starch molecule into a chunky and denser branched structure, thereby slowing down the rate of starch digestion. By controlling the modified substrate, the two-stage treatment of firstly modifying the granular starch and then modifying the gelatinized starch can achieve the purpose of enhancing the modification effect of the starch branching enzyme, and further increase the content of the slow-digesting raw starch in the modified starch. Reducing the digestion rate of starch provides ideas for the preparation of slow digesting starch by biomodification.

Description

A Modification Method for Improving Slow Digestibility of Starch

technical field

The invention relates to a modification method for improving slow digestibility of starch, which belongs to the field of bio-modified starch.

Background technique

As the main source of energy for humans and most animals, starch is often used in food, medicine, textile and other industrial fields. In contemporary society, consumers are increasingly pursuing nutrition and health. Foods that can maintain a sense of satiety after ingestion and provide energy continuously and slowly meet the needs of consumers. The slow-digestible starch in natural starch can be absorbed slowly and release energy continuously after being ingested by the human body, avoiding the violent fluctuation of blood sugar, conforming to the current food development trend, and having a great market application prospect as a food raw material.

However, in the process of food processing, natural starch undergoes heating, irradiation, decoction and other processes, the structure of starch granules is destroyed, and the anti-digestion performance is sharply weakened, making it difficult to meet the requirements of modern consumers. The modification of starch by physical, chemical or biological methods can change the molecular structure of starch, thereby improving the digestibility of starch and making it meet the needs of healthy diet. Among them, the biological enzyme method has the advantages of substrate specificity and is the most widely used. Starch branching enzyme (Branchingenzyme; BE; EC 2.4.1.18) is a glycosyltransferase belonging to glycoside hydrolase 13. It first hydrolyzes the α-1,4 glycosidic bond on the substrate molecule, and cuts the linear glucan fragment, and then transfer the cut fragment to the remaining substrate molecule by transglycosylation, forming an α-1,6 glycosidic bond.

In the previous reports, the treatment conditions of starch branching enzyme modification are relatively simple, and there is still a lot of room for improvement in the digestibility of modified starch. The invention improves the slow digestion performance of the modified starch by optimizing the modification process.

Contents of the invention

In order to increase the content of slow-digesting starch, the present invention provides a modification method for improving the slow-digesting performance of starch. Starch molecular structure is changed by starch branching enzyme, which has smaller branched chain and higher branching degree, so as to slow down Purpose of starch digestion. More importantly, by controlling the modified substrate, a two-stage treatment of modifying granular starch and then modifying gelatinized starch is adopted to achieve the purpose of enhancing the modification effect of starch branching enzymes and further improving the slow digestion rate of modified starch. Increase the content of raw starch, reduce the digestion rate of starch, and provide ideas for the preparation of slow-digestible starch by biomodification.

The biological modification method for increasing the content of slowly digested starch of the present invention mainly includes the following steps: after preheating the starch milk sample at 50-60°C for 10-15min, adding 20-50U/g starch branching enzyme, Treat at ℃ for 4-20 hours, put it in a boiling water bath for gelatinization and inactivate the enzyme, then place it at 50-60℃ for preheating for 10-15min, add 20-50U/g starch branching enzyme and treat it at 50-60℃ for 4- After 20 hours, the reaction was terminated, and the modified starch was obtained by drying.

In one embodiment of the present invention, the starch milk sample is preheated at 50-60°C for 10 minutes, then 20-50 U/g of starch branching enzyme is added, treated at 50-60°C for 4-20 hours, and placed in boiling water After 30 minutes of gelatinization in the bath to inactivate the enzyme, preheat at 50-60°C for 10 minutes, add 20-50U/g starch branching enzyme, treat at 50-60°C for 4-20 hours, terminate the reaction, and dry to obtain modified starch.

In one embodiment of the present invention, the starch may be common corn starch.

In one embodiment of the present invention, the mass concentration of the starch milk is 5%.

In one embodiment of the present invention, the pH of the starch milk is adjusted to 7.0-8.0.

In one embodiment of the present invention, the amount of starch branching enzyme added is 20-50 U/g starch on a dry basis.

In one embodiment of the present invention, the sample added with starch branching enzyme is treated at a constant temperature of 50-60°C.

In one embodiment of the present invention, the source of the starch branching enzyme is Geobacillus thermoglucosidans STB02.

Beneficial effects of the present invention:

The present invention utilizes starch branching enzyme to transform the elongated starch molecule into a chunky and denser branched structure, thereby slowing down the rate of starch digestion. By controlling the modified substrate, the two-stage treatment of firstly modifying the granular starch and then modifying the gelatinized starch can achieve the purpose of enhancing the modification effect of the starch branching enzyme, and further increase the content of the slow-digesting raw starch in the modified starch. Reducing the digestion rate of starch provides ideas for the preparation of slow digesting starch by biomodification.

Detailed ways

Determination of starch digestibility:

Weigh 0.6g of starch and 50mg of guar gum into a centrifuge tube, add 10mL of pepsin (5mg/mL enzyme solution prepared with 0.05M HCl), shake in a 37°C water bath at 160r/min for 30min, then add 10.0ml 0.25M sodium acetate buffer solution, 30 glass beads (d=5mm), mix well, then add 5mL enzyme mixed solution (pancreatic amylase 64.5×10 ³ Ceralpha Units/g starch, glucoamylase 167U/g starch), at 37 °C in a water bath.

After reacting for 20 min and 120 min respectively, 250 μL of the reaction solution was mixed in 10 mL of 66.6% ethanol, the mixture was centrifuged at 3500 rpm for 5 min, and 100 μL of the supernatant was taken to determine the glucose content (glucose oxidase GOPOD method). In addition, after 120 minutes of reaction, the sample was shaken and placed in a boiling water bath for 30 minutes. After cooling, 10.0ml of 7M KOH was added and placed at 4°C for 30 minutes. Take 0.5ml of the above mixture in 5.0mL of 0.5M acetic acid, add 84μL of amyloglucosidase, react at 70°C for 30min, then bathe in boiling water for 10min. Add 20mL of water to dilute, centrifuge at 1500rpm for 5min, take 0.1mL supernatant to measure the glucose content. The specific calculation formula is as follows:

RDS＝ _G20 ×0.9

SDS＝(G ₁₂₀ -G ₂₀ )×0.9

RS = (TG - G ₁₂₀ ) × 0.9

In the formula: RDS—fast digestible starch content;

SDS—slow digestible starch content;

RS—resistant starch content;

G ₂₀ —glucose content produced after amylase hydrolysis for 20 minutes;

G ₁₂₀ —glucose content produced after amylase hydrolysis for 120 minutes;

TG—total glucose content in starch after enzymatic hydrolysis

Comparative Example 1: Effects of Starch Branching Enzyme Modification on Slow Digestible Starch Content in Starch Milk

Dissolve cornstarch in water to prepare 5% starch milk, preheat at 50°C for 10min, add 30U/g starch branching enzyme, treat at 50°C for 10h, gelatinize in a boiling water bath for 30min, terminate the reaction, freeze-dry to obtain the improved permanent starch. The results of the modified starch digestibility test are shown in Table 1.

The reaction results showed that starch branching enzyme modification can improve the digestibility of corn starch milk. After starch branching enzyme treatment for 10 hours, the content of fast digestible starch in the modified starch decreased significantly, while the content of slow digestible starch and resistant starch increased significantly. Compared with the control (without starch branching enzyme treatment), the content of fast-digesting starch decreased by 8.4%, the content of slow-digesting starch increased by 29.5%, and the content of resistant starch increased by 17.5%. It indicated that enzyme modification of starch branching could improve the slow digestibility of the product, and the modified highly branched structure increased the steric hindrance of starch and delayed the digestion and hydrolysis of the enzyme. However, the current level of slowly digestible starch is not enough to meet the needs of the food industry, and there is still room for further improvement.

Comparative Example 2: Effects of Starch Branching Enzyme Modification on Slow Digestible Starch Content in Starch Paste

Dissolve cornstarch in water to prepare 5% starch milk, gelatinize in boiling water for 30 minutes, add 30 U/g starch branching enzyme, preheat at 50°C for 10 minutes, treat at 50°C for 10 hours, stop the reaction in a boiling water bath for 30 minutes, freeze-dry Obtain modified starch. The results of the modified starch digestibility test are shown in Table 1.

Table 1 reaction result shows, is modified 10h with gelatinized cornstarch as substrate, and the content of slowly digestible starch reaches 24.6% in the prepared modified starch, improves 77.0% compared with contrast, compares comparative example 1 (cornstarch granule as the substrate) further increased by 36.7%; the fast digestible starch content increased by 20.4% compared with Control Example 1 (corn starch granules as the substrate) further increased by 13.1%.

Comparative Example 3: Effects of Starch Branching Enzyme Modification on Slow Digestible Starch Content in Starch Paste

Dissolve cornstarch in water to make 5% starch milk, gelatinize in boiling water for 30 minutes, add 30 U/g starch branching enzyme, preheat at 50°C for 10 minutes, treat at 50°C for 20 hours, stop the reaction in a boiling water bath for 30 minutes, freeze-dry Obtain modified starch. The results of the modified starch digestibility test are shown in Table 1.

Show from reaction result, carry out modification 20h with gelatinized cornstarch as substrate, in the modified starch that makes, slow digestible starch content reaches 25.4%, compare contrast and improve 82.7%, compare comparative example 1 (cornstarch granule is substrate) was further increased by 15.0%. It shows that compared with the modification of granular starch as the substrate, the modification effect of starch branching enzyme modification with gelatinized starch as the substrate is more significant. The destruction of starch granules is conducive to the full reaction of substrates and enzymes, which significantly improves the slow digestibility of products.

Example 1: Effect of Two-stage Modification on Slowly Digestible Starch Content in Starch

Dissolve cornstarch in water to prepare 5% starch milk, preheat at 50°C for 10min, add 30U/g starch branching enzyme, treat at 50°C for 10h, gelatinize in boiling water bath for 30min, preheat at 50°C for 10min Finally, add 30 U/g starch branching enzyme, treat at 50°C for 6 hours, stop the reaction in a boiling water bath, and freeze-dry to obtain modified starch. The results of the modified starch digestibility test are shown in Table 1.

The results of the reaction show that the two-stage modification with granular cornstarch and gelatinized cornstarch as substrates respectively, the content of slow-digestible starch in the prepared modified starch reaches 26.0%, which is 87.0% higher than that of the control. Example 3 (gelatinized cornstarch as substrate) further increased by 2.4%; fast digestible starch content increased by 23.9% compared to control example 3 (gelatinized cornstarch as substrate) further increased by 2.3%.

Example 2: Effect of two-stage modification on slow-digestible starch content in starch

Dissolve cornstarch in water to prepare 5% starch milk, preheat at 50°C for 10min, add 30U/g starch branching enzyme, treat at 50°C for 10h, gelatinize in boiling water bath for 30min, preheat at 50°C for 10min Finally, add 30 U/g starch branching enzyme, treat at 50°C for 8 hours, stop the reaction in a boiling water bath, and freeze-dry to obtain modified starch. The results of the modified starch digestibility test are shown in Table 1.

The results of the reaction showed that cornstarch was modified using a two-stage modification strategy, and the content of fast-digestible starch in the prepared modified starch reached 54.8%, which was further reduced by 5.0% compared with the control example 3 (gelatinized cornstarch was the substrate). %; Slowly digestible starch content reaches 26.3%, which is further increased by 3.5% compared with control example 3 (gelatinized corn starch is substrate); resistant starch further increases by 11.8% compared with control example 3 (gelatinized corn starch is substrate) .

Example 3: Effect of Two-stage Modification on Slowly Digestible Starch Content in Starch

Dissolve cornstarch in water to prepare 5% starch milk, preheat at 50°C for 10min, add 30U/g starch branching enzyme, treat at 50°C for 10h, gelatinize in boiling water bath for 30min, preheat at 50°C for 10min Finally, add 30 U/g starch branching enzyme, treat at 50° C. for 10 h, stop the reaction in a boiling water bath, and freeze-dry to obtain modified starch. The results of the modified starch digestibility test are shown in Table 1.

The results of the reaction show that cornstarch was modified using a two-stage modification strategy, and the content of fast-digestible starch in the prepared modified starch reached 53.8%, which was further reduced by 6.8% compared with the control example 3 (gelatinized cornstarch was the substrate). %; Slowly digestible starch content reaches 26.5%, which is further increased by 4.3% compared with control example 3 (gelatinized corn starch is substrate); resistant starch is further increased by 16.6% compared with control example 3 (gelatinized corn starch is substrate) . It shows that the two-stage modification process is conducive to further improving the slow digestibility of the product, and the slow digestibility of the product is enhanced with the increase of gelatinization time.

Digestibility of each modified sample in table 1

The results of the reaction showed that the two-stage modification strategy was used to modify the granular corn starch and gelatinized corn starch as substrates, and the content of fast digestible starch in the modified starch was 53.8%, which was 27.4% lower than that of the control; The content of slowly digestible starch was 26.5%, which was 90.6% higher than that of the control; the resistant starch was 64.2% higher than that of the control. Comparative Example 3 and Example 3 illustrate that compared with the modification of gelatinized starch, the two-stage modification strategy of first granulation and then gelatinization can significantly increase the content of slow-digestible starch in modified starch, and is an effective method to improve the starch branching enzyme modified product. Strategies for medium and slow digestible starch content.

The above results indicated that the modification of starch with starch branching enzyme was beneficial to increase the content of slowly digestible starch in starch and improve the digestibility of starch after gelatinization. More importantly, the two-stage modification strategy can effectively improve the modification effect of starch branching enzymes and significantly increase the slow-digestible starch content in the product.

Although the present invention has been disclosed above with preferred embodiments, it is not intended to limit the present invention. Any person familiar with this technology can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore The scope of protection of the present invention should be defined by the claims.

Claims (8)

1. A method for improving slow digestibility of starch, characterized in that it mainly comprises the following steps: after preheating the starch milk sample at 50-60°C for 10-15min, adding 20-50U/g starch branching enzyme, Treat at ~60°C for 4-20h, place in a boiling water bath for gelatinization and inactivate enzymes, place at 50-60°C for preheating for 10-15min, add 20-50U/g starch branching enzyme and treat at 50-60°C After 4-20 hours, the reaction is terminated, and the modified starch is obtained by drying. 2. A method for improving slow digestibility of starch according to claim 1, characterized in that, after preheating the starch milk sample at 50-60°C for 10 minutes, add 20-50U/g starch branching enzyme, Treat at ~60°C for 4-20h, put it in a boiling water bath for gelatinization for 30min to inactivate the enzyme, then place it at 50-60°C for preheating for 10min, add 20-50U/g starch branching enzyme and treat it at 50-60°C for 4 -20h, terminate the reaction, and dry to obtain modified starch. 3. A method for improving slow digestibility of starch according to claim 1 or 2, characterized in that said starch is common cornstarch. 4. A method for improving starch slow digestibility according to claim 1 or 2, characterized in that the starch milk mass concentration is 5%. 5. A method for improving slow digestibility of starch according to claim 1, 2 or 4, characterized in that the pH of the starch milk is adjusted to 7.0-8.0. 6. A method for improving the slow digestibility of starch according to any one of claims 1 to 5, characterized in that the source of the starch branching enzyme is Geobacillus thermoglucosidans STB02. 7. A method for improving slow digestibility of starch according to claim 1 or 2, characterized in that, after preheating the starch milk sample at 50°C for 10 minutes, add 20-50U/g starch branching enzyme, Treat at ℃ for 6-10h, put it in a boiling water bath for 30min to inactivate the enzyme, put it at 50℃ for preheating for 10min, add 20-50U/g starch branching enzyme and treat at 50℃ for 6-10h to terminate the reaction. Dry to obtain modified starch. 8. A method for improving slow digestibility of starch according to claim 7, characterized in that, after preheating the starch milk sample at 50°C for 10 minutes, add 30U/g starch branching enzyme and treat it at 50°C for 8. -10h, gelatinize in a boiling water bath for 30min to inactivate the enzyme, preheat at 50°C for 10min, add 30U/g starch branching enzyme, treat at 50°C for 8-10h, terminate the reaction, and dry to obtain modified starch.